CT: indicated to evaluate for glenoid bone stock, glenoid orientation and degree of fatty infiltration of RTC. Must have at least 25mm of bone from the glenoid face to the most medial cortex of the scapula to provide seating of the glenoid implant for reverse TSA. (Frankle m, JBJS 2005;87A:1697).

MRI

Goutallier Classification of Muscle Atrophy (Goutallier D, CORR 1994;304:78). -Stage 0=completely normal muscle. -Stage 1=muscle contains some fatty streaks. -Stage 2=fatty infiltration is important, but there is still more muscle than fat. -Stage 3=there is as much fat as muscle. -Stage 4=more fat than muscle is present.-Degeneration is grade at the tip of the coracoid process and at the inferior margin of the glenoid and the values are averaged to determine the stage.